Comment 59 for bug 943263

I have a similar problem: right after boot, my screen works (displays kernel messages) until maybe drm module is loaded (I guess by udev), then it becomes immediately blank and monitor is blinking, and then works again some time after fbcon and radeon modules are manually loaded in boot scripts (before starting X).
It depends on modeset=1; if I use modeset=0 this behaviour doesn't appear, bua X cannot run without KMS.

I have an AMD A4-3300 APU and using a (vanilla) linux kernel 3.5.3 (on Slackware64)

The real problem is that some time (a couple of minutes or so) after video adapter is in idle mode (e.g. if I am not using the PC), monitor blinks (as in low power mode) screen is blank and system is no longer recoverable (unless I use e.g. ssh just to power it off).
I don't know if the two problems are really related or not. Voltage problems?

I have these messages in dmesg, too, when it happens:
"""
[ 2405.888198] [drm:radeon_atom_encoder_dpms], encoder dpms 33 to mode 0, devices 00000001, active_devices 00000001
[ 2405.892352] [drm:radeon_dp_get_link_status], link status 44 44 01 00 44 44
[ 2405.892360] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
[ 2405.892365] [drm:dp_get_adjust_train], using signal parameters: voltage 0.4V pre_emph 3.5dB
[ 2405.893921] [drm:radeon_dp_get_link_status], link status 44 44 01 00 48 44
[ 2405.893926] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.4V pre_emph 6dB
[ 2405.893931] [drm:dp_get_adjust_train], using signal parameters: voltage 0.4V pre_emph 6dB
[ 2405.895508] [drm:radeon_dp_get_link_status], link status 44 44 01 00 4c 44
[ 2405.895514] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.4V pre_emph 9.5dB
[ 2405.895518] [drm:dp_get_adjust_train], using signal parameters: voltage 0.4V pre_emph 9.5dB
[ 2405.897079] [drm:radeon_dp_get_link_status], link status 44 44 01 00 41 44
[ 2405.897085] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.6V pre_emph 0dB
[ 2405.897089] [drm:dp_get_adjust_train], using signal parameters: voltage 0.6V pre_emph 0dB
[ 2405.898632] [drm:radeon_dp_get_link_status], link status 44 44 01 00 45 44
[ 2405.898634] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.6V pre_emph 3.5dB
[ 2405.898636] [drm:dp_get_adjust_train], using signal parameters: voltage 0.6V pre_emph 3.5dB
[ 2405.900152] [drm:radeon_dp_get_link_status], link status 44 44 01 00 49 44
[ 2405.900155] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.6V pre_emph 6dB
[ 2405.900156] [drm:dp_get_adjust_train], using signal parameters: voltage 0.6V pre_emph 6dB
[ 2405.901674] [drm:radeon_dp_get_link_status], link status 44 44 01 00 42 44
[ 2405.901676] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.8V pre_emph 0dB
[ 2405.901677] [drm:dp_get_adjust_train], using signal parameters: voltage 0.8V pre_emph 0dB
[ 2405.903194] [drm:radeon_dp_get_link_status], link status 44 44 01 00 46 44
[ 2405.903196] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.8V pre_emph 3.5dB
[ 2405.903197] [drm:dp_get_adjust_train], using signal parameters: voltage 0.8V pre_emph 3.5dB
[ 2405.904715] [drm:radeon_dp_get_link_status], link status 44 44 01 00 43 44
[ 2405.904717] [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 1.2V pre_emph 0dB
[ 2405.904718] [drm:dp_get_adjust_train], using signal parameters: voltage 1.2V pre_emph 0dB
[ 2405.906235] [drm:radeon_dp_get_link_status], link status 44 44 01 00 43 44
[ 2405.906238] [drm:radeon_dp_link_train_cr] *ERROR* clock recovery reached max voltage
[ 2405.906240] [drm:radeon_dp_link_train_cr] *ERROR* clock recovery failed
"""